Most influenza experts agree that we are "due" for an influenza pandemic. One potential method of protecting public health in the threat of a pandemic would be mass immunization. The research program being proposed will evaluate the feasibility of developing, manufacturing, and distributing a live attenuated vaccine which could ultimately be tested in humans for potential use during an influenza pandemic. The objective will be to test the hypothesis that vaccination with a live attenuated vaccine based on a pandemic virus strain is a feasible and practical way of controlling the spread of influenza during a threat of a pandemic. Aviron is developing a live attenuated vaccine for general use in the prevention of influenza, and is interested in applying this technology to pandemic preparedness efforts in developing a vaccine candidate, as well as building related competencies to ensure widespread vaccination is feasible. Specifically, this research program will determine: the feasibility of generating reassortants containing HA and NA genes derived from avian influenza virus and remaining genes from the cold-adapted A/Ann Arbor/6/60 virus using classic reassortment technique; the characterization and safety evaluation of the reassortants in vitro and in animal models; manufacturing such a vaccine including the release protocols to ensure appropriateness for human testing; the potential for usefulness (in providing safety and efficacy) of the vaccine candidate in providing protection in humans; and the methods required for rapid, efficient distribution and administration of the vaccine to large numbers of people.